Once a new physical disk is added to a Linux host, it needs to be presented to the OS.
This is a five step process:
Daily Archives: October 25, 2012
Linux – rescanning the SCSI bus
When new SCSI devices are added to a Linux system, it is necessary to re-scan the SCSI bus so that the OS can add them to the device list:
[root@localhost ~]# ls /dev/sd* /dev/sda /dev/sda1 /dev/sda2 /dev/sda3 [root@localhost ~]# su -c 'for hst in $(ls /sys/class/scsi_host) ; do echo "- - -" > /sys/class/scsi_host/$hst/scan ; done' [root@localhost ~]# ls /dev/sd* /dev/sda /dev/sda1 /dev/sda2 /dev/sda3 /dev/sdb [root@localhost ~]#
Disassembling The Oracle Data Block
Back in 2005 I got interested in reverse engineering the Oracle data block.
I had already spent far too much time breaking apart the redo blocks, and had published an interesting paper on the matter called Disassembling the Redo Block which Frank Naude over at orafaq was kind enough to host for me. This was back before “blogging” became the ubiquitous pass time of Oracle DBAs it appears to be today.
Rich Niemiec at TUSC forwarded to me an interesting article on the Terilingua Block Viewer for Oracle, and so after a lot of searching around I found the BBED tool. What’s more, BBED was included in the standard Oracle distribution for Windows and Linux. On Linux all you had to do was link it.
And so armed with an old IBM Aptiva running Linux 8 Pro and a copy of Oracle 9i, I set about trying to figure out how the blocks of a database held together.
The result was a detailed analysis of BBED and how to use it. Although obsolete today, the article is still interesting to those DBAs who want to understand the inner working of Oracle. At the time it was quite popular, being cited by Pete Finnegan and Don Burlseon among others.
I include it here for posterity.
And no, you still have to work out the password for yourself 🙂
the gruffdba 